package string;

/**
 * @BelongsProject: LeetCode
 * @BelongsPackage: com.elvis.leetcode.string
 * @Author: Elvis
 * @CreateTime: 2020-02-19 08:41
 * Description: Integer to Roman
 * Roman numerals are represented by seven different symbols: I, V, X, L, C, D and M.
 *
 * Symbol       Value
 * I             1
 * V             5
 * X             10
 * L             50
 * C             100
 * D             500
 * M             1000
 * For example, two is written as II in Roman numeral, just two one's added together.
 * Twelve is written as, XII, which is simply X + II. The number twenty seven is written as XXVII, which is XX + V + II.
 *
 * Roman numerals are usually written largest to smallest from left to right. However, the numeral for four is not IIII.
 * Instead, the number four is written as IV. Because the one is before the five we subtract it making four.
 * The same principle applies to the number nine, which is written as IX. There are six instances where subtraction is used:
 *
 * I can be placed before V (5) and X (10) to make 4 and 9.
 * X can be placed before L (50) and C (100) to make 40 and 90.
 * C can be placed before D (500) and M (1000) to make 400 and 900.
 * Given an integer, convert it to a roman numeral. Input is guaranteed to be within the range from 1 to 3999.
 *
 * Example 1:
 * Input: 3
 * Output: "III"
 *
 * Example 2:
 * Input: 4
 * Output: "IV"
 *
 * Example 3:
 * Input: 9
 * Output: "IX"
 *
 * Example 4:
 * Input: 58
 * Output: "LVIII"
 * Explanation: L = 50, V = 5, III = 3.
 *
 * Example 5:
 * Input: 1994
 * Output: "MCMXCIV"
 * Explanation: M = 1000, CM = 900, XC = 90 and IV = 4.
 */
public class Leetcode12 {
    /**
     * 功能描述: 在leetcode讨论区看到的大佬的神奇的思路
     * 〈〉
     * @Param: [num]
     * @Return: java.lang.String
     * @Author: elvis
     * @Date: 20-2-19 上午9:33
     */
    public String intToRoman(int num) {
        String M[] = {"", "M", "MM", "MMM"};
        String C[] = {"", "C", "CC", "CCC", "CD", "D", "DC", "DCC", "DCCC", "CM"};
        String X[] = {"", "X", "XX", "XXX", "XL", "L", "LX", "LXX", "LXXX", "XC"};
        String I[] = {"", "I", "II", "III", "IV", "V", "VI", "VII", "VIII", "IX"};
        return M[num/1000] + C[(num%1000)/100] + X[(num%100)/10] + I[num%10];
    }

    public String intToRoman2(int num) {
        int[] values = {1000,900,500,400,100,90,50,40,10,9,5,4,1};
        // 将每一种数字单位表示出来　再for循环一一进行匹配关联
        String[] strs = {"M","CM","D","CD","C","XC","L","XL","X","IX","V","IV","I"};

        StringBuilder sb = new StringBuilder();

        for(int i=0;i<values.length;i++) {
            while(num >= values[i]) {
                //逐一匹配　字符串一一append
                num -= values[i];
                sb.append(strs[i]);
            }
        }
        return sb.toString();

    }

    public String intToRoman3(int num) {
        // 哈哈　俺自己的全遍历　列出所有的情况单位　以空间换时间
        String[] str = {"MMM","MM","M","CM","D", "CD", "CCC","CC","C", "XC","L","XL","XXX","XX","X", "IX", "V", "IV","III","II","I"};
        int[] nums = {3000,2000,1000,900,500,400,300,200,100,90,50,40,30,20,10,9,5,4,3,2,1};
        String ans = "";
        for (int i = 0; i< nums.length; i++){
            if(num >= nums[i]){
                num -= nums[i];
                ans += str[i];
            }
        }
        return ans;
    }
}
